Insulating glazing (IG) units, such as windows and doors, are typically formed of two or more glass panes separated by a spacer. The spacer can contain desiccant that keeps the interior of the IG unit free of moisture during its service life. To increase the insulating properties of the IG unit, the space between the glass panes it typically filled with an insulating gas, such as argon or krypton.
For aesthetic reasons, some IG units include muntin bars inside of the gas space established by the spacer. The muntin bars, which may also be called glazing bars or sash bars, divide a single window into a grid system of small panes of glass, called lites. Typical muntin bar patterns include grids of rectangles, squares, or diamonds. Muntin bars create the visual appearance that the window is formed of multiple, small pieces of glass joined together by the muntin bars instead of large, unitary panes of glass. This replicates the appearance of early windows and doors, which were formed of small panes of glass joined together instead of large unitary panes of glass, which were more expensive and difficult to manufacture.
In practice, muntin bar assemblies are usually formed by cutting individual pieces of muntin bar from longer sections of muntin bar stock and then joining the individual pieces together to form a grid pattern. This may involve cutting each individual piece to a required length, cutting the ends of the muntin bar to allow different pieces to be joined together in abutting arrangement, and cutting away sections of the muntin bar to allow different pieces of muntin bar to be laid over one another in overlapping arrangement. In high-volume production facilities where muntin bar assemblies of the same size, shape, and pattern are produced over and over, tooling and equipment can be arranged to repeatedly cut the specific pieces of muntin bar required to make the muntin bar assembly.
While manufacturers can arrange equipment to repeatedly produce identical muntin bar assemblies, consumers are increasing demanding more customized and varied fenestration products. These customized products often include muntin bar assemblies with non-standard sizes, shapes, patterns, and types of muntin bar. Fabricating each muntin bar assembly on a customized basis can be a time consuming and costly process.